The effect of different oxidative challenge on growth and stress protein induction in Escherichia coil

The influence of six oxidative agents (cadmium, hydrogen peroxide, t-butyl hydroperoxide, cumene hydroperoxide, peracetic acid, paraquat) on growth an d induction of stress proteins using two-dimensional gel electrophoresis wa s analysed in Escherichia coli K-12 (strain MG1655). Treatment of exponenti ally growing cultures with 273 mu M cadmium, 2 mM hydrogen peroxide, 0.1 mM t-butyl hydroperoxide, 0.1 mM cumene hydroperoxide, 0.05 mM per acetic aci d, and 0.075 mM paraquat caused complete but transient growth inhibition. S tasis lasted for about Ih, after which cells recovered and resumed growth a ccompanied by changes in the rates of synthesis of a large number of protei ns. During growth arrested phase, each stress factor presumably represented a unique signal of oxidative stress and induced a specific set of proteins , some of which were found to be induced by more than one oxidative stress condition. The induction of two subgroups of (i) immediate proteins (either transiently or permanently synthesized stress proteins), and (ii) late pro teins which appeared only 2.5 h after the addition of the oxidative agent w as observed. The exponentially growing cells of E. coli were able to better resist the higher concentrations of oxidative agents than were the lag pha se cells. The effect of oxidative agents appeared to depend on the growth p hase at which stress was initiated. Cadmium-pretreated cells were found to recover more rapidly during subsequent stress conditions, such as hydrogen peroxide, t-butyl hydroperoxide, cumene hydroperoxide, peracetic acid, but not paraquat. The production of proteins induced by six oxidative agents is discussed in view of the mechanism of cell adaptation.